I think that your constraints rather define a Directed Acyclic Graph with a single source and a single sink, which is more general than a one-dimensional chain. More conditions to constrain the edges at each node to just one incoming and one outgoing may
be needed to match the explanation.

Also, looking at it, it made me think of Peano's axioms to define integers as a chain.

Kind regards,

Ghislain

From: Costello, Roger L. [costello@mitre.org]Sent: Monday, February 20, 2017 4:17 PMTo: xml-dev@lists.xml.orgSubject: [xml-dev] Large class of problems: constrain a bunch of pieces to form a chain

Hi Folks,

There are a large class of problems that may be characterized this way: Given a bunch of pieces, constrain them so they form a single, connected chain.

The following is a beautiful example from this class of problems.

Problem: Constrain the segments in an aircraft’s route so that they form a single, connected chain.

Explanation: An aircraft flies a route. A route consists of segments. A route has a starting fix and an ending fix. A “fix” is a position. Each segment also has a starting fix and an ending fix. One segment’s starting fix must match the route’s starting
fix. One segment’s ending fix must match the route’s ending fix. For the other segments, they must be connected: the ending fix of one segment must be the starting fix of another segment.